Difference Between Structural Testing and Functional Testing

What is Functional Testing?

Before we dive into the main topic which is “Difference Between Structural Testing and Functional Testing”, we need to understand the definition of functional testing. The fundamental capabilities of a software application are put to the test in a manner known as functional testing. This type of software testing is carried out in accordance with a set of requirements that has been established in advance. Functional tests, which utilise Black Box Testing techniques, check to see if a given input results in the desired output, regardless of any other details that may be involved. The results are either binary, meaning the tests passed or failed.

Why is Functional Testing Important?

Testing your application’s functionality is essential because, without it, you run the risk of not having an accurate understanding of whether or not it functions as intended. If an application does not provide the key expected outputs to the end-user, then the application cannot be considered to be working, even if it passes non-functional tests and otherwise performs well.

What is the Difference between Functional and Non-Functional Testing?

Functional tests examine an application to determine whether or not the specified functional requirements have been met, whereas non-functional tests examine aspects of an application that are not functional, such as its performance, security, scalability, or quality. To put this another way, functional testing is concerned with determining whether or not key functions are operating, whereas non-functional testing is more concerned with determining how operations are carried out.

Examples of Functional Testing Types

When you are testing your application, there are a lot of different kinds of functional tests that you might want to complete. The following are some of the most frequent:

1. Unit Testing

Unit testing is a type of software testing that involves breaking the desired result down into its component parts. This allows you to determine whether or not a limited number of inputs (or even just one) can produce the desired output. Because each unit test is intended to cover only a single section of code (a function, method, object, etc.) and verify its functionality, they tend to be among the smallest tests to write and execute quickly. This is because each test is designed to cover only a single section of code.

2. Smoke Testing

Smoke testing is carried out with the purpose of ensuring that the application’s most vital components function as designed. This is the first round of testing, and its scope is not meant to cover everything that could possibly be tested. The application’s functionality on the most fundamental level is validated using smoke tests. In the event that this is not the case, there is no reason to advance to more detailed testing; instead, the application can be sent directly back to the development team so that it can be reviewed.

3. Sanity Testing

The purpose of sanity testing is similar to that of smoke testing in that it is meant to verify fundamental functionality and may help to circumvent the need for in-depth testing of software that is already broken. Sanity checks, on the other hand, are carried out much later in the process in order to determine whether or not a newly implemented change to the code has produced the desired result. A “sanity check” is performed on a particular change in order to determine whether or not the newly implemented code roughly performs as expected.

4. Integration Testing

Integration testing determines whether combinations of individual software modules function properly together. Individual modules may already have passed independent tests, but when they are dependent on other modules to operate successfully, this kind of testing is necessary to ensure that all parts work together as expected.

5. Regression Testing

This testing is to ensure addition of new code will not disrupt the functionality of previously built-in features. To put it another way, did the quality of your application “regress” as a result of the new code, or did it go in the opposite direction? The modifications that were made are the focus of regression tests, which also verify that the application as a whole continues to behave in the expected manner and is stable.

6. User Acceptance Testing (UAT)/Beta Testing

Putting your application through its paces in a production setting with a select group of actual customers is an essential part of usability testing. The feedback from these live users, who have not previously used the application and may discover critical bugs that were unknown to internal teams, is used to make further changes to the application before it is fully launched. These live users have not previously used the application.

7. UI/UX Testing 

Testing of the application’s graphical user interface and user experience (UI/UX) is performed. It is necessary to test the functionality of user interface components like menus, buttons, text fields, and others in order to guarantee that the application’s users will have a positive experience when utilising the software. Testing the user interface and user experience, also known as visual testing, can either be done manually or automatically. Black box testing, white box testing, component testing, application programming interface (API) testing, system testing, and production testing are some of the other subcategories of functional testing.

Structural Testing

We also need to know what is structural testing before we jump into the main topic which is “Difference Between Structural Testing and Functional Testing”. Code structure is tested by a sort of testing called structural testing. It is often referred to as Glass Box or White Box testing. The majority of developers perform this kind of testing because it necessitates a working knowledge of the code. Instead of focusing on the system’s functionality, it is more interested in how it accomplishes its tasks. It gives the tests additional coverage. For instance, in order to evaluate the trigger condition for a certain error message in an application, there must be numerous triggers. While testing the SRS requirements, it is possible to miss one. However, as structural testing seeks to cover all the nodes and paths in the structure of code, it is most likely that the trigger will be covered by this testing.

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It works well in conjunction with Functional Testing. With the help of this method, the test cases that have been drafted in accordance with the system requirements can first be analysed, and then additional test cases can be added in order to make the coverage greater. It can be utilised on a variety of levels, including testing at the unit level, testing at the component level, testing at the integration level, testing at the functional level, etc. It is helpful in conducting comprehensive testing on software using this. The majority of the structural testing is performed by automation.

Difference Between Structural Testing and Functional Testing

Structural Testing	Functional Testing
Structural testing is always carried out manually.	Functional testing can be carried out manually or automatically.
Internal code structure is not taken into consideration when designing structural test cases, which are based on external specifications.	Functional testing would be based on the component’s internal operations as well as external specifications.
Input/output conditions serve as the basis for structural test cases.	Functional test cases are built around the operations a component is capable of.
Errors in the application of data structures and internal coding logic are discovered using structural testing.	Functional testing ensures that the system complies with accepted information processing standards and is error-free.
After maintenance teams have finished coding, structural testing is carried out.	During development and/or maintenance, functional testing is carried out.
Data values are not dependent on structural test cases.	Functional test cases might need to use a particular value in order to pass or fail (error checking).
The foundation of structural test cases is hardware level error checking.	Software techniques are used to perform functional testing.
Static algorithms and data structures are used in structural testing.	Object-oriented programming and dynamic data structures are both analysed during functional testing.
Error finding and correction are addressed by structural testing.	Quality characteristics like dependability, maintainability, security, etc., may be addressed by functional testing.
The primary focus of structural testing is on logical mistakes or bugs in the code.	Verifying that the system complies with the requirements is the main goal of functional testing.
The data flow analysis methodologies are the foundation of the structural testing tool.	The Event Analysis methodology serves as the foundation for the functional testing tool.
The functional components of an application, such as a text display feature and how it interacts with other features, are tested using structural testing.	Functional testing is done based on the application’s business requirements, and it examines the user’s acceptance criteria to see how well the system satisfies those needs.
Low-level software modules and components are subject to structural testing.	The entire software system is put through functional testing in accordance with the necessary requirements.
According to the requirement criteria, structural testing does not recognise any boundary conditions.	All boundary conditions are acceptable in functional testing.
Instead of focusing on the actions that a component can take, structural testing examines input/output conditions.	Functional testing looks at how an application functions within its business domain and meets user needs.
The main purpose of structural testing is to examine how well modules communicate with one another.	In functional testing, a system’s ability to fulfil a specific business purpose or set of related purposes is assessed.
Functional Testing has measurable standards for success or failure.	The outcome of structural testing may be subject to subjective interpretation.
A software development team usually executes structural test cases.	Business analysts and testers create functional test cases.
The internal design of the module under test is revealed by structural testing. Consequently, it can offer useful information for enhancing the internal architecture of the module or software application.	Functional testing aids in finding flaws that could cause a company to lose money by providing information on how well the system satisfies user needs.
Systems that are interconnected are tested using structural testing.	Stand-alone applications could be tested using functional testing.

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Conclusion

It is evident that the uses of structural testing and functional testing are distinct from one another. Although each type of testing is necessary in its own way to produce reliable software applications, they are very different from one another.

References

Board, S. E. (2021, December 15). Difference Between Structural and Functional Testing 2023. SoftwareTestingo – Interview Questions, Tutorial & Test Cases Template Examples. Retrieved February 5, 2023, from https://www.softwaretestingo.com/structural-and-functional-testing/

Shain, D. (2022, May 13). What is Functional Testing? Types and Example (Full Guide). Automated Visual Testing | Applitools. Retrieved February 5, 2023, from https://applitools.com/blog/functional-testing-guide/

What is Structural Testing? Software Testing Class. (2016, December 19). Software Testing Class. Retrieved February 5, 2023, from https://www.softwaretestingclass.com/what-is-structural-testing/